In addition to Lafora's Disease, there are numerous single-gene defect storage diseases that have devastating effects on the children of adult carriers (e.g. Niemann-Pick disease, Tay-Sachs disease, Fabry disease, and many other Lysosomal Storage disorders). A common feature of these disorders is that an enzyme deficiency (and the intracellular accumulation of undigested metabolites) leads to progressive neurologic deterioration and early death. In all cases, the mutated gene and enzyme deficiency is known. But copies of the potentially life-saving genes sit dormant in research laboratories because of problems in delivery and expressing an exogenous gene throughout the brain. Large molecule therapeutics alone do not cross the brain capillaries, leading to the perception that the blood-brain barrier (BBB) may be an insoluble problem. Complications seen with viral vector-delivery of gene therapies further suggest that new methods need to be devised for the delivery of large-molecule genes across the BBB. We propose to use recently developed immunoliposome BBB delivery systems to successfully deliver a normal gene therapeutically through the BBB of knock-out mice with Lafora's Disease, via intravenous administration. If this non-viral delivery system can treat the disease in animal models, an immunoliposome-based cure for this fatal inclusion body disorder could be developed for clinical use. The aims are: (1) To prepare pegylated immunoliposomes (PIL) and establish BBB delivery of a) an exogenous gene and b) delivery of the normal EPM2a/laforin gene, in mice bearing a significant inclusion body burden. (2) To demonstrate transplacental and fetal brain delivery of an exogenous gene after i.v. administration to the dam. (3) To confirm uniform delivery of the laforin gene to the brain of knock-out mice after a single intravenous injection, and determine how Lafora-body burdens change. And (4) to develop an optimal therapeutic regimen of multiple i.v. injections which suppresses Lafora body burdens for 6-12 months in knock-out mice. Examinations of BBB integrity and capillary tight-junctions will show the absence of microvascular pathology, even after chronic PIL treatments